Watch the Sonora Spring: Verse 1 online guitar lesson by John Jorgenson from Gypsy Jazz Journeys: Sonora Spring
The fourth phrase starts again with an open B string, playing four sixteenth notes, and then we move up to the 7th fret and vibrato. Then there's a turn - a quick little ornament hammering-on and pulling off the 7th and 6th frets - landing on the 5th fret. From there, climb down chromatically for the rest of the phrase. Chromatic is just a complicated phrase for "one fret lower", referencing the chromatic scale which moves by half steps.